Neurological is another disability classification that you could look into. Depending on the state and the evaluator giving the Dx, ADHD, slow processing speed, DCD can end up there, too.
Schools are not allowed to simply transition kids on IEPs for developmental delay straight to LD at age nine. They have to re-qualify them under some other disability. The original intent was to reduce stigma for students identified with disabilities, by avoiding the application of heavy-duty labels at a young age, when it's not entirely clear what is really going on, and to cast a slightly wider net to catch disabilities before students fall as far behind in academics. So the idea was specifically to allow some students to outgrow (or really, be remediated out of) early delays without trapping them in special education for their entire careers--which for many underprivileged kids restricts their access to the broadest range of instruction. It was a response both to the desire to prevent further failure as early as possible, and to the issue of equity and disproportionality in special education (over-identification of poor and minority children).
Like many well-intentioned initiatives, there have been unintended consequences.
